The use of thin-film semiconductor chips has been steadily gaining prevalence in recent years, especially in the production of radiation emitting components such as LEDs and lasers or IR diodes.
Such a thin-film semiconductor chip is described for example in DE 100 59 532. In its production, a light-emitting diode structure is grown on an epitaxial substrate and then bonded to an acceptor substrate, and the light-emitting diode structure is then separated from the epitaxial substrate. Heretofore, the method used to release the film, once it has been bonded to the acceptor substrate, has usually been to first thin the epitaxial substrate by grinding and then to remove the rest of the epitaxial substrate in an etching step. The original epitaxial substrate is completely destroyed in the process.
A further method of separating gallium nitride thin films is described in U.S. Pat. No. 6,420,242. In that method, a gallium nitride structure is deposited on a sapphire wafer, and this gallium nitride layer is bonded to an acceptor substrate and then heated by exposure to laser light. This heating causes local destruction of the crystal structure in the region of the gallium nitride. The release of gaseous nitrogen, combined with further heating to melt the residual gallium, causes the thin film to separate from the epitaxial substrate. However, this type of method has been practicable heretofore only in connection with the use of gallium nitride layers to fabricate thin-film chips, since heating gallium nitride layers permits the release of nitrogen in gaseous form.